Letter of the Law
by Mountain King
Summary: Some times Castle's more outlandish theories actually make more sense than the truth, after all not even he could come up with this one. Crossover with the 2003 TMNT series


Letter of the Law

Introduction

Writers block is, as many of us know all too well, a cast iron pain. In my case I write the same paragraph over and over again. Each time with only one or two words changed. The same one or two words, flip flopping from one to the other. No matter what I do I agonise over the same handful of words until I throw the whole thing into the corner and brood about it.

The only way I've found to break this block is to take a sharp left turn. Write for a show that I've not done before. So here we go with an experiment.

This is one of three stories, all loosely connected to one another as part of a series. It's not quite a trilogy, not quite stand alone. They're all Turtles Crossovers but with different shows so, unfortunately, you'll have to see my bio to pull them all together.

* * *

Disclaimer

Teenage Mutant Ninja Turtles was created by Kevin Eastman & Peter Laird and is owned by Mirage Comics. Kim Possible on the other hand was created by Andrew W. Marlowe and is owned by Disney. Really, look it up.

* * *

The murder board was full and at the same time empty. They had four victims. Four. And the same number of clues. The same damn thing four times, a short throwing dagger left in the victims but it wasn't what killed them. All had their necks broken expertly and were left in the street.

'This is a tough one.' Castle said, handing her a coffee as usual. 'Any leads.'

'Still nothing. No witness, no connection, zilch.' Kate admitted taking a sip. She'd worked dead end cases before but never multiple murders. Never something this brutal.

'At least there's some good news.' Castle said softly. Even he knew this was bad and for once he wasn't trying to get on her nerves.

It wasn't enough. 'Good news, how can anything be good about this Castle?'

'No victim number five.'

She gave him a sharp look 'You're right, but if we don't get a lead soon we won't be able to stop it.'

Castle gave her a half smile. 'You'll stop them Kate, you always do.'

As usual Ryan and Esposito took that moment to bust in on them. 'Any results?' She asked them. The two of them had been canvassing chinatown. The throwing daggers had a short length of hand stitched cloth tied to it. Each length had identical symbols sewn into them.

They'd tried everything, but there was no match in their system or any system they had access to. Castle had noted that the dagger itself looked Japanese, a cross check showed he was right. The other two detectives had combed Chinatown and any expert they could find. 'No. If someone does know they ain't saying anything.' Ryan collapsed in his chair.

'You sure?' Castle asked.

'We were out all night bro.' Esposito yawned. 'You think you can do better. You try.'

Kate looked at the two of them. They were wrecked. 'Damn. Good work you two.' She stared at the murder board. 'Dead end.'

'Are you absolutely sure you tried everyone?' Castle was insistent. 'No one was talking?'

'No one, why.' Ryan asked.

Kate frowned, there was something about the way Castle was digging. 'You know someone, don't you?'

Castle looked guilty, 'For the record, no. But there might be someone.'

'Wait, we were out all night and you might know someone.' Ryan was back on his feet. 'Do you know what I'm going to have to promise Jenny to apologise?'

'Ah, ah. Might. I said might.' Castle backed off. 'Even if he wanted to talk to me and he did know something he would not be my first choice of contacts.'

'We've tried everyone Castle.' Kate put her coffee down. 'If you have the slightest lead we're on it.'

'Yeah, preferably before we spend a night up to our necks in dead fish.' Esposito growled. Both Kate and Castle turned to face him. 'Don't ask.' he said

'Really don't ask.'

'So that's that smell.' Kate took shallow breaths.

Castle shrugged. 'I wasn't going to say anything.'

'No, you were going get your contact.' Kate ordered. 'Now Castle, bring him in.'

The writer winced, he really wanted to avoid calling whoever this was. 'It doesn't work that way. I need go in person and this can not on any official record.'

'Who is this guy?' Kate asked.

'Unofficial. Very unofficial.' he told them, pulling one of the evidence photos from the board. 'Call you when I got something.'

'No, we'll call when we have something.' Kate disagreed grabbing her coat. 'I'm coming with you.'

Castle spun on her. 'I don't think I was clear. You do not want to meet this guy. I mean ever.'

'Sorry Castle, rules.' Kate told him. 'If this is going to be an anonymous informant I need to be able to vouch for them.'

'You're kidding. She's joking.'

Esposito shook his head. 'Wish she was. We don't record the name, but if we reach out to someone that can't be recorded, it's on us.'

'Oh this is going to be very bad.' He said.

* * *

Kate, following Castle's directions, stopped outside a old Brownstone deep in the city. Getting out of the car she looked up at the shop sign. 'An antiques shop. Miles from anywhere close to anything a small second hand slash antiques shop?'

'Okay, I don't have a direct line, but the owner of this place does.' Castle opened the door for her and she went in. It was like walking into Aladdin's Cave, if it was full of junk. Cool looking junk, but junk. There was everything here, if she ever needed to redecorate she'd have to remember this place.

An attractive red-head was busy polishing a wooden mantelpiece clock. It looked like the store owner had just finished repairing it. She looked up, 'Mr Castle, looking for some more props for your mother?'

'Wish I was. I, we need help.' He asked. 'From, your friends.'

The owner's eyes flashed in Kate's direction. 'The only help I can give is with antiques. Or computers.'

'Okay.' Kate pulled out her badge and the evidence photo. 'Castle thinks you, or someone you know, can tell us about this.'

The owner paused, 'Detective?'

'Kate Beckett and you are?'

'April O'Neil. I don't know what Mr Castle has told you but…'

Kate interrupted. 'He hasn't told me anything but you are.'

Castle actually stopped her mid attack. 'Kate, let me. Look O'Neil, April, we've tried everything, I promise. We have overturned every stone. Your friend is our last chance.'

'You want to get him involved in a police investigation? Are you crazy?'

'Four people are dead miss O'Neil and right now you are our only lead to stop a fifth.' Kate pressed.

'Four.' O'Neil repeated. 'This is about the murders I saw on the news. It said you had no leads.'

'That's it.' Castle pointed at the photo. O'Neil took a deep breath and looked at both of them.

'I'll talk to him and call you if he has anything, but you have to keep this out the papers and reports. He and the boy's do not exist.'

Kate was really curious now, but she kept her poker face straight. 'If it gets me an arrest I don't care.' She pulled out a contact card and handed it to O'Neil.

Behind them the door opened and a very rough, somewhat familiar voice shouted. 'Yo April, you in here?'

Kate turned around and recognised the hooligan. 'Casey Jones. It's still a small world.'

The back alley thug stumbled. 'Err. Officer Beckett. What are you doing here?'

'It's detective now, just following a lead.'

'You two know each other?' Castle asked.

Kate grinned. 'Jones here has a very long record with the law. I arrested him twice myself when I was on the beat. Think masked vigilante, he had a one man war against any number gangs out there. But he's been off the grid for a while now, thought you left town?'

'I did. but I came back.' He admitted. 'The guy's needed some help and that's what I do.'

'Help?' Kate said disbelievingly. 'The only help you do Jones involves trying to take someones head off with a baseball bat.'

'No,' O'Neil spoke up. 'He helps me. Lifting, some of my antiques can be heavy.'

Jones nodded. 'Yeah, thats me. Some things need a delicate touch.' As if to demonstrate he picked up a vase by the door and promptly dropped it. Shattering against the floor.

'Casey.' O'Neil sighed.

Kate didn't believe a word of it, but didn't have any evidence. Or a crime. 'Okay, well good to catch up with you again Jones. Miss O'Neil time may be of the issue.' With that she left, Castle following. Once outside she pulled out her phone and hit contacts.

'Esposito, it's Beckett. I need you to run a name for me. April O'Neil. She owns a second hand shop, check for any gang affiliations.'

'Kate, what are you doing?' Castle jumped.

She ignored him. 'Yes and cross reference that with a Casey Jones. He's on the system. We're on our way back.'

'Kate you promised.'

'I promised I wouldn't investigate their friend. Not them.' she told him. 'Come on Castle lets get back to the station.'

* * *

Back at the station Esposito had the file ready. 'No gang affiliations and nothing connected to Jones.'

'Told you, their on the straight and narrow.' Castle insisted.

'Can I finish?' Esposito asked, 'There is one little thing. The place was bombed a year or more back. Investigation said it was a gas leak, but there was a call from a beat cop just before. Said there was a cross between world war three and a bruce lee film was going on in there.'

Kate ripped the report from the other detective's hands 'What?'

'We're looking for ninjas, I'd say we were looking in the right place.' Esposito finished. Kate flipped through it again. It didn't make any sense, Gang war zones didn't just spring out of nowhere. There was mounting tension, violent attacks, even a few deaths on both sides. There was no evidence of any of that. Just one day someone decided to blow up a shop. A shop that was rebuilt without a problem and just kept going about it's business.

'Alright Castle spill. You know more than you're telling us. Who is April O'Neil and what does she have to do with all of this?'

'Nothing, I told you she's just the best way to contact my… contact.' Castle pleaded. 'Look you guys trust me right, well believe me there are some things you don't want to know and these people and what they do is right up there.' He sat on the edge of her desk. 'If they point us in the right direction that's the best we can hope for.'

'And if they are a suspect?'

'What?'

Kate shook her head. 'We have to consider it Castle. If one guy in the whole city is the only one that can decipher that symbol then either he wrote it, or it was meant for him. That's why I have to know who it is, to eliminate him from our enquiries.'

Castle actually looked terrified, it hadn't occurred to him. He was still a long way from big a real detective. 'No way. No chance.'

'In a case like this everyone's a suspect Bro.' Esposito told him.

Castle refused to even listen. 'Not my guy. I promise.'

But Kate was going to open his eyes if it killed her. 'How many times have we gone after the wrong suspect because the real killer fed us a line? You have to admit anyone connected has to be a suspect.'

'I'm not saying he couldn't kill. Hell Splinter could kill everyone in this station and we wouldn't be able to slow him down on his own, but there is absolutely no way he did this.'

Kate caught his slip, and was fairly sure everyone else had to. 'So his name is Splinter. That's somewhere to start, Ryan see what you can find out.'

'You won't find him.' Castle told them without a trace of doubt. 'He won't be on any system.'

* * *

Kate hated it when Castle was right. He was always smug when he was. It was annoying. They had found nothing. No name, real or otherwise, with any connection to New York what so ever. Eventually she gave up and waited.

Nearly half the day had been wasted when her phone rang. 'Kate Beckett.' she answered

'Detective Beckett, this is April O'Neil.' The young woman sounded a bit nervous and something else. She was worried.

Kate tried to keep her voice friendly, 'Miss O'Neil I wasn't expecting to hear back from you so soon.'

'Yeah well I sent Casey with the photo you gave me. He could tell it was important.'

So whoever it was knew Jones as well, Kate filed that fact away. That could even have been how those two met. 'It is, thank you.'

'Well it's even more important than what you think. Our friend, his name's Master Splinter, he's in your basement.'

Kate blinked, trying to figure out what she just heard. 'I'm sorry, what?'

'He wants to talk to you and Mr Castle. He's in the storage basement of the Twelfth Precinct. That's were you are, right? He want's to see the message to, if you could bring it.'

She quickly flashed back to Castle's warning 'You want me to go into a storage room and meet with a shadowy character alone and bring our only real evidence with me?'

O'Neil didn't say anything for a long second. 'Look I know how this sounds, but if it wasn't important we wouldn't ask.' Over the years Kate had learnt to trust her instincts, and despite everything her training and common sense told her she believed O'Neil was on the level. 'I'll meet him.'

'Thanks, oh and detective he's very shy, so you won't see him. Not unless he wants you to.' With that she hung up.

Putting the phone down Kate looked up, Ryan and Esposito were ready to complain. 'Hold on, I know what you're going to say.'

'This is loco.' Esposito told her

Ryan agreed. 'We don't know anything about this guy.'

'Castle does.' She pointed out and looked over the the Writer bringing them fresh coffee's.

'What?'

* * *

'This is a bad idea. A really bad idea.' Castle was telling her. 'We've done some stupid things in the past but this really is stupid.'

'You've been saying that for five minutes Castle, look they asked for just the two of us and that's what they're getting. Ryan and Esposito will just happen to be near if we need them.' She checked her gun, just because she was trusting didn't make her a fool. 'You got the dagger?'

'Of course.'

'Then let's go.' she nodded to the other two detectives and went inside. The basement was mostly given over to morgue but there were a couple of disused storage rooms. Both were supposed to be locked but one had been opened. It wasn't hard to guess which one they were expected in.

Kate slid into the room her sidearm holstered, but her hand close. 'Hello. I'm Detective Kate Beckett?' she called into the room. There was a single light on but most of the room was lost in deep shadows.

'I am here Detective.' The voice was old, worn and accented and came from the darkness.

'From what Castle and Miss O'Neil told me you didn't like police officers.'

There was a pause. 'I am not welcome in your world Detective Beckett. Just as I feel you would not be welcome in mine.'

The sound was moving, she tried following it but all she could see was the briefest of flickers. 'Then why are you here, talking to me?'

'Because once again my world and yours have overlapped. Mr Castle'

'Y… Yes.' Castle stepped into the light

'I must see the message. Hold it out, please.' For once Castle did as he was asked and it vanished. It was like the shadows themselves had swallowed the dagger. She hadn't taken her eyes off it for a second. Now she could see why her partner was nervous.

'You're saying theses murders are a message, who to? Why this way?' she asked the darkness.

'No. The deaths are a challenge, this is the message.'

This time Kate could have sworn she saw something move. She spun and snapped on her flashlight, but there was nothing. 'You've got to show yourself some time.' She challenged. 'There is only one way in or out and we have it covered.'

'Perhaps.' Came the quiet voiced answer, this Splinter would make a expert poker player if his face was as composed as his voice. 'Why have you tried to trap me?'

'Four dead bodies, and our only lead is a Japanese immigrant with no record in any system. You tell me.'

'This killer is a coward. He strikes the unwary and innocent as an insult. He kills not for any truer reason than to kill. He is challenging my master, Hamato Yoshi, by leaving his mark with the bodies.' Gone was that clam edge. This Splinter was angry and ready to go out there. 'I will be the one to deal with this, there will be no more deaths.'

Kate knew that tone. 'You're going to kill him, what will your master say about that?'

'My Master Yoshi is long dead. It falls to me to answer in his memory.' Splinter replied and again Kate filed that fact away.

'Killing someone, even a multiple murderer, is still a crime.' Kate tried to coax them out of the shadows. 'Tell me what you know and we can arrest him.'

'I do not know who it is that leaves these, but I will find out.'

'Then we can work together. There is no need to hide.' She said, but before this Splinter could reply there was the sound of something heavy slumping to the ground, twice.

'What was that?' Castle asked in an urgent whisper.

Kate had a horrible suspicion. 'Esposito? Ryan? You still out there.'

'Sorry lady.' A new, very much gruffer, voice replied from outside the room. 'Your friends are having a little impromptu nap time. You comin' Master Splinter?'

'Patience Raphael, my son.' Splinter replied, still invisible in the darkness. 'Detective you are quite correct, and quite wrong. We cannot work together, but to kill the murderer would too be crossing a line. We will subdue him, you can then have him. Await a call from us.'

That's when she saw it. A silhouette, just as he, it, was leaving the room. At least five foot tall, slightly hunched over and walking on what could be best described as it's legs. It had a long nose pointing forward and sharp ears rising high above it's head. It had a stocky walking stick and a long slender tail poking out of some sort of jacket. 'Goodbye detective.' It said in that same accented english and then, with a calm nod it was gone.

* * *

Kate stared at her desk. Somewhere behind her Esposito and Ryan were complaining to Castle. 'What the hell happened?'

He bought one of him sons with him.' Castle explained. 'He got the drop on you.'

'His son? Why didn't we see him.' Ryan asked.

Castle paused for a moment. 'You probably wouldn't want to.'

'That what happen to Beckett.'

'She saw him, and she's like that?'

'Yep.'

'So how you dealing bro?'

'Seen them before. Took half a bottle of whiskey to try and get over it the first time.'

Kate swallowed. 'Did it work?' she asked, not looking away from the desk.

'Nope. But then I realised if these guys were going to be anywhere it would be New York.' Castle told her. 'You back with us?'

'No, nowhere close.' She admitted, finally forceing herself to blink. 'What the hell did I just see Castle?'

Ryan joined in. 'Yeah tell us.'

'Sworn to secrecy guys. Sworn to secrecy' Castle sat down next to her.

Ryan came around, still holding a Ice pack to the back of his head. 'Well you're not, are you Beckett. So what did you see.'

Kate froze, trying to find the words to explain. To describe what she had seen in a fleeting instant, but her mind absolutely refused to help. Eventually she gave up. 'Find out everything you can about a Hamato Yoshi, probably an immigrant. I want to know if he is dead, how he died and if there was an investigation.'

Ryan looked to Esposito and after a moment they got to work. Once the pair of them were buried into the research she finally looked at Castle. 'I can't tell them. I can't even.'

'Been right there.' Castle shrugged, thankfully he wasn't being his usual annoying self. 'You'll get over it.'

'No I won't, I had no idea. I mean…'

He put his hand on hers. 'Don't think about it.' It was the best advice anyone could give.

But it was easier said than done. 'How'd you meet them?'

'I was out doing research, just before I met you. Looking for inspiration. I'd just killed off Derrick Storm and I was lost. Literally and figuratively. Found myself in the wrong part of town and they were there. The rest is history.'

Kate nodded. 'I can see that. Just tell me this is the weirdest thing you've seen.'

He snorted. 'Oh by a long way. Four big green ninja,' he suddenly dropped his voice 'Turtles. Nothing can top that.'

'Turtles?' Kate asked. 'I saw…'

'Their father, he's a big…'

'Ah.' she interrupted him that one word was going to give her nightmares. 'That's all I needed to know.' Kate looked back at her team. 'How long do you think it's going to take them to find the killer?'

'Hard to say, why.'

Kate had a powerful need to clock off for the day, use a sick day and drink a bar dry. She was about to suggest it when her phone rang.

End Letter of the Law


End file.
